1. Field of the Invention
The present invention relates to a distance measuring system containing a solid-state image sensing device functioning as a distance measuring sensor and also relates to a distance measuring method.
2. Description of the Related Art
Known conventional applications of image sensors include technologies using a time-of-flight (TOF) method for measuring a distance to a target object in a contactless manner. In one known technology using the TOF method, photoelectrons (negative electric charge) generated in a photoelectric conversion element are allocated and then read out. The emission waveform of an LED does not rise and fall sharply but gradually at a slope, and this property is utilized in Japanese Laid-Open Patent Publication No. 2004-294420. This patent document discloses that a distance is measured using stored photoelectrons generated by a pulsed light received in a rise time period during which the intensity of the pulsed light changes and also using stored photoelectrons generated by a pulsed light received in a time period during which the intensity of the pulsed light is constant.